1. Technical Field
The invention relates to methods and materials involved in the determination of the function of a nucleic acid based on its sequence.
2. Background Information
The ability of the various genome projects to acquire gene sequence data has far outpaced the ability to ascribe biological functions to these new genes. This dilemma has led to the concept of “functional genomics” which can be defined as the attempt to match biological function with gene sequence on a genome scale. Since many biological processes are well conserved in evolution, model organisms for which rapid genetic tools have been developed can be used as model systems to identify human genes. For example, genes with specific biological roles are identified first in the model organism, and then genome databases are used to identify human homologues.
A useful model system for the study of vertebrate biology is the zebrafish Danio rerio. Aspects of the zebrafish developmental process that render the zebrafish useful as a model system include rapid development of the organ systems, transparent embryos, embryos that develop outside the womb, and availability of a large number of embryos. Furthermore, the sequence of the zebrafish genome is expected to be completed by the end of 2002. Assignment of function based on sequence information would be greatly facilitated by the development of a rapid, targeted, knockdown technology in this model vertebrate.
Recently, a number of strategies have been developed for selectively repressing the expression of specific genes. These methods are based on inducing degradation of cognate mRNAs by introduction of double-stranded RNA into cells or addition of single stranded antisense RNAs that trigger mRNA degradation by RNase H. Although these methods have been used in D. melanogaster and C. elegans, they have been unsuccessful in fish due to toxicity, nonspecific effects, or the inability to achieve uniform distribution for gene repression.